Anti-inflammatory imidazoles

ABSTRACT

2,4- AND 4,5 - DIARYLIMIDAZOLES AND ACID ADDITION SALTS THEREOF, A NOVEL CLASS OF ANTI-INFLAMMATORY AGENTS.

United States Patent 01 lice 3,772,441 ANTI-INFLAMMATORY IMIDAZOLES Joseph George Lombardino, Niantic, Conn., assignor to Pfizer Inc., New York, N.Y.

No Drawing. Original application Nov. 16, 1970, Ser. No. 90,077, now Patent No. 3,707,475, dated Dec. 26, 1972. Divided and this application May 8, 1972, Ser.

Int. Cl. A61k 27/00 US. Cl. 424-473 21 Claims ABSTRACT OF THE DISCLOSURE 2,4- and 4,5 diarylimidazoles and acid addition salts thereof, a novel class of anti-inflammatory agents.

CROSS REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 90,077, filed Nov. 16, 1970, now US. Pat. 3,707,475.

BACKGROUND OF THE INVENTION This invention relates to polyarylimidazoles, and more particularly to a series of 2,4 diaryl-S-substituted-, 4,5- diaryl-2-substituted-imidazoles and their alkylation products and the acid addition salts thereof, possessing chemotherapeutic activity and to the method of inhibiting inflammation in mammals with said agents.

Aryl substituted imidazoles have been known in the chemical literature for some time and have been reported to possess varied properties. 2,4,5-triarylimidazoles claimed as antifertility agents have been synthesized by Bhaduri, et al., Indian J. Chem., 4, 419 (1966); sedative properties are reported by Lespagnol et al., Chem. Therap., 1, 292

-( 1966), and antitubercular activity by Deliwala et al.,

Proc. Ind. Acad. Sci., 31, 107 (1950) for a series of 2,4,5- triarylimidazoles. No utility as anti-inflammatory agents has been disclosed.

The use of polyarylimidazoles as phototropic agents possessing chemiluminescent characteristics has appeared extensively in the literature. Cook et al., J. Chem. Soc., 278 (1941), reports the synthesis of a number of 2-substituted-4,S-diphenylimidazoles, wherein the 2 substituent is alkyl or aryl, which have chemiluminescent properties, and 2,4,5-triarylimidazo1es are claimed in French Pat. 1,351,818, Belgian Pat. 5 85,555 and German Pat. 1,106,- 599 to possess phototropic, electrophotographic and xerographic utility, respectively.

White et al., J. Org. Chem., 29, 1926 (1964) reported the synthesis of a series of 2-substituted-phenyl-4,S-diphenylimidazoles, using the procedure of Davidson et al., J. Org. Chem., 2, 319 (1937), in an elfort to study the infrared characteristics of this class of compounds. More recently, Ogata et al., J. Org. Chem., 34, 3981 (1969), during a kinetic study, synthesized a number of nuclear substituted 2,4,5-triphenylimidazoles. No utility was disclosed during either study.

SUMMARY OF THE INVENTION The anti-inflammatory agents of this invention are represented by the formulae:

and the acid addition salts thereof, where:

Ar and A are each selected from the group consisting of furyl, thienyl, pyridyl, phenyl and substituted phenyl 3,772,441 Patented Nov. 13, 1973 Of particular interest, because of their usefulness as antiinflammatory agents, are congeners of Formula I wherein Ar and Ar are each phenyl or substituted phenyl wherein said substituent is fluorine, chlorine, bromine, alkyl, alkoxy or alkylthio each containing from 1 to 4 carbon atoms; R is hydrogen or alkyl containing 1 to 4 carbon atoms; and R is trifluoromethyl. Also of interest are those antiinflammatory agents of Formulae II and III wherein Ar, Ar and R are each phenyl and substituted phenyl where said substituent is fluorine, chlorine, bromine, alkyl, alkoxy or alkylthio each containing from 1 to 4 carbon atoms and R is hydrogen. Also, compounds of the present invention, surprisingly, have shown excellent activity as inhibitors of platelet aggregation.

Also considered within the scope of this invention are compounds of the formulae:

Ar\ 0 F; Ar Ar I and V N 0 F3 R3 R4 (I and the alkylation products thereof, wherein Ar and Ar are as previously indicated and R and R when considered separately are lower alkyl or trifluoromethyl and R and R when taken together with the carbon atom to which they are attached form a ring containing from 6 to 8 carbon atoms which can be interrupted by the hetero atom S, O or NH.

DETAILED DESCRIPTION 'OF THE INVENTION In accordance with the process employed for preparing the polyarylimidazoles of the present invention of the Formulae I, H and III:

wherein Ar, Ar and R are as previously defined and R is hydrogen, the following scheme is illustrative:

AlC]C-AI" RaCHO CHsCO|NH -0 I and .Ar-C-fiJ-R; ArCHO CHaCOaNHa Hand III Both the above illustrated reactions are conducted under similar reaction conditions, which are essentially those as employed by Davidson et al., J. Org. Chem., 2, 319 (1937), and comprise heating a mixture of an a-diketone, an aldehyde or derivative thereof and ammonium acetate in a solvent of glacial acetic acid. As much as a five to ten-fold excess of ammonium acetate can be employed. The amount of aldehyde used in relation to the diketone can vary from an equimolar amount to as much as a 100% excess.

In general, reflux temperatures are considered desirable although lower temperatures with correspondingly longer reaction periods are operable. When said reflux temperatures are employed reaction times of 1-5 hours are adequate to yield the desired product.

A convenient method for isolation of the product comprises dilution of the reaction mixture with' water followed by neutralization with ammonium hydroxide to a pH of approximately 7. The resulting precipitate is then filtered, dried and recrystallized from an appropriate solvent.

The requisite a-diketones of the type II II Ar-C-C-Ar' are either commercially available, or can easily be synthesized either by oxidation of the corresponding u-hydroxyketone according to the method as taught by Clarke et al., Organic Syntheses, coll. vol. I, John Wiley & Sons, Inc., New York, N.Y., 1942, p. 87, or by a selenium dioxide oxidation of the monoketone as taught by Hatt et al., J. Chem. Soc., 93 (1936). The a-hydroxyketones, in turn, are commercial reagents or are prepared by the methods as outlined by Ide et al., Organic Reactions, vol. IV, John Wiley & Sons, Inc., New York, N.Y., 1948, p. 269, while the monoketones are commercial reagents or are synthesized according to the methods outlined by Gore, Friedel-Crafts and Related Reactions, vol. III, Interscience Publishers, New York, N.Y., 1964, chapter 31.

a-Diketones of the type II II Ar--C-CR; wherein R is lower alkyl and trifluoromethyl, are similarly synthesized by oxidation of the corresponding acyloins of the formula i Ar-CHOHCR1 or by the aforementioned selenium dioxide method. Acyloin intermediates leading to the products of the instant invention are prepared by the methods outlined by Me- Elvain, Organic Reactions, vol. IV, John Wiley & Sons, Inc., New York, N.Y., 1948, p. 256, while the monoketone precursor can be prepared as taught by Nes et al., I. Am. Chem. Soc., 72, 5409 (1950).

The requisite aldehydes are industrial chemicals or prepared by the methods as taught by Carnduff, Quart. Rev. 20, 169 (1966).

A second, and equally useful, alternate route to the products of the present invention comprises condensation of an amidine with an a-haloketone as illustrated.

wherein Ar, Ar and R are as previously described and X is chlorine or bromine and R is hydrogen.

The alternate synthetic method is essentially that as taugh't'by Krieg et al., Chem. Ber., 100, 4042 (1967) and comprises treating an aqueous solution of an appropriate amidine hydrohalide, preferably hydrochloride, with an equimolar amount of the requisite a-haloketone dissolved in a water immiscible solvent, such as chloroform, methylene chloride or carbon tetrachloride, followed by the addition of two moles of an alkali metal hydroxide. In general, reflux temperatures are favored, although lower temperatures with corresponding longer reaction times are operable. Reaction times vary with the concentration, temperature and reactivity of the respective reactants, and are generally from 15 minutes to 4 hours.

The product is conveniently isolated by separation of the nonaqueous phase and evaporation to dryness. The residual solid product can be purified by column chromatography or by simple recrystallization depending on the degree of purity of the crude.

The requisite a-haloketones necessary for the above described alternate synthesis are commercial agents or can be made from the corresponding ketone via bromination according to the methods outlined by Wagner et al., Synthetic Organic Chemistry, John Wiley & Sons, Inc., New York, N.Y., 1958, p. 100. The appropriate ketones are prepared by the methods outlined by Gore, Friedel- Crafts and Related Reactions, vol. III, Interscience Publishers, New York, N.Y., 1964, chapter 31.

The amidines employed in the alternate route to the products of the present invention are synthesized by the methods as outlined by Wagner et al., Synthetic Organic Chemistry, John Wiley & Sons, Inc., New York. N.Y., 1958, p. 634.

A characteristic of the compounds of the present invention of the Formulae I, II and III wherein R is hydrogen is the acidic nature of said hydrogen and the property to form salts with basic reagents such as alkali metal hydroxides, alkoxides or hydrides and alkali earth metal hydroxides.

It is these above described basic salts which can be alkylated giving rise to compounds related to I, II and III where R is alkyl and alkenyl. Said salts can be formed in situ or can be preformed and isolated prior to their alkylation.

In practice, a solution of the unalkylated imidazole in a highly polar, aprotic solvent such as dimethylformamide, dimethylsulfoxide, or hexamethylphosphoramide is treated with at least an equivalent amount of an alkali metal alkoxide or hydride such as sodium methoxide or sodium hydride, thus forming the corresponding sodium salt in situ. The alkyl or alkenyl halide, either chloride, bromide or iodide, is added, usually in an aprotic solvent, to the solution or suspension of the requisite salt of the imidazole. At least an equimolar amount of alkylating agent is added, plus as much as a 10-50% excess.

Reaction temperatures are not critical, but for convenience the reaction mixture is heated at steam bath temperatures for 1-5 hours. Following the completion of the reaction, the product is isolated by dilution of the reaction mixture with water and filtration. Alternately, the product can be extracted from the diluted reaction using water immiscible solvents such as benzene or chloroform.

The isolated products can be further purified by recrystallization from a suitable solvent.

The imidazoles of Formulae II and III where R is hydrogen are equivalent because of the tautomeric nature of the acidic hydrogen as illustrated:

However, once alkylation has been carried out on the imidazole, tautomerization through migration of the alkyl group is impossible. A more detailed discussion of this concept is provided by Schipper et al., Heterocyclic Compounds, vol. V, R. C. Elderfield, ed., John Wiley & Sons, Inc., New York, NY. (1957), chapter 4, p. 198.

Thus, during alkylation of the imidazoles it can be noted that two positional isomers are frequently formed due to the difference in the nature of the Ar and R substituents.

In the case of such experimental results, the mixture of isomers is recovered by methods known to those skilled in the art. In many of the preparations disclosed wherein a solid, often crystalline material, separates from the reaction mixture, the solid appears to consist predominantly of one of the isomers. Said isomer can be purified by repeated recrystallization from a suitable solvent to a constant melting point. The other isomer, the one present in smaller amounts in the originally isolated solid material, is the predominant product in the mother liquor. It can be recovered therefrom by methods known to those skilled in the art, as for example, the evaporation of the mother liquor and repeated crystallization of the residue to a product of constant melting point. Alternatively, the reaction mixture can be extracted either before or after evaporation to dryness.

Although said mixtures may be separated by methods known to those skilled in the art, for practical reasons it is advantageous to use said mixtures as they are isolated from the reaction. Further, it is frequently advantageous to purify these mixtures of isomers by at least one recrystallization from an appropriate solvent or by trituration in an appropriate solvent. Said recrystallization or trituration thus allows the separation of the mixture of positional isomers from such extraneous materials as starting material and undesirable by-products.

The identification of the isomers has not been completed. Both isomers of a given compound, however, exhibit the same type of activity, e.g., as anti-inflammatory agents.

As has been previously mentioned, the compounds of the present invention wherein R is hydrogen can form salts with basic reagents. In addition to this characteristic, irnidazoles wherein R is hydrogen, alkyl or alkenyl can also, as previously mentioned, form acid addition salts. Said basic compounds of the present invention are converted to the acid addition salts by interaction of the base with an acid either in an aqueous or nonaqueous medium. In a similar manner, treatment of the acid addition salts with an equivalent amount of an aqueous base solution, e.g., alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates or with an equivalent amount of a metal cation which forms an insoluble precipitate with the acid anion, results in a regeneration of the free base form. Such conversions are best carried out as rapidly as possible and under temperature conditions and method dictated by the stability of said basic products. The bases thus regenerated may be reconverted to the same or a different acid addition salt.

In the utilization of the chemotherapeutic activity of those compounds of the present invention which form salts, it is preferred, of course, to use pharmaceutically acceptable salts. Although water-in'solubility, high toxicity, or lack of crystalline nature may make some particular salt species unsuitable or less desirable for use as such in a given pharmaceutical application, the water insoluble or toxic salts can be converted to the corresponding pharmaceutically acceptable bases by decomposition of the salt as described above, or alternately they can be converted to any desired pharmaceutically acceptable acid addition salt.

Examples of acids which provide pharmaceutically acceptable anions are hydrochloric, hydrobromic, hydroiodic, nitric, sulfuric, or sulfurous, phosphoric, acetic, lactic, citric, tartaric, succinic, maleic, and gluconic acids.

6 As previously indicated, the polyarylimidazoles of the present invention are all readily adapted to therapeutic use as anti-inflammatory agents in mammals. Outstanding for their effectiveness in this regard include the following agents:

2-trifluorometh'yl-4,5-bis(p-methoxyphenyDimidazole, 2-trifluoromethyl-4,5-bis (p-methylthiophenyl) imidazole, 2-trifluoromethyl-4,5-bis(p-n-butoxyphenyl)imidazole, 2-trifluoromethyl-4,5-bis 3,4-dimethoxyphenyl) imidazole, 2-trifluoromethyl-4,5-bis p-ethoxyphenyl imid azole, 2-trifluoromethyl-4,5-bis (p-bromophenyl) imidazole, 2-trifluoromethyl-4,5-bis (o-methoxyphenyl) imidazole, 2-trifluoromethyl-4,5-bis(m-methoxyphenyl) imidazole, 2-triflu oromethyl-4,5-bis(p-fluorophenyl) imidazole, 2-trlfluoromethyl- 4,5 -bis p-tolyl imidazole, 2-trifluoromethyl-4-phenyl-5- p-bromophenyl imidazole, 2-trifluoromethyl-4-phenyl-5- (p-methoxyphenyl) imidazole, 1-methyl-2-trifluoromethyl-4,S-bis (p-methoxyphenyl) imidazole and 2- (p-bromophenyl) -4, S-diphenylimidazole.

A standard procedure for detecting and comparing anti inflammatory activity of compounds in this series and for which there is an excellent correlation with human efiicacy is the carrageenin rat foot adena test, of Winter et al., Proc. Soc. Exp. Biol., 111, 544 (1962), whereby unanesthetized adult male albino rats of 150-190 g. body weight are each numbered, weighed and marked with ink on the right lateral malleolus. One hour after administration of the drug by gavage, edema is induced by injection of 0.05 ml. of 1% solution of carrageenin into the plantar tissue of the marked paws. Immediately thereafter, the volume of the injected paw is measured. The increase in volume three hours after the injection of carrageenin constitutes the individual response. Compounds are considered active if the difference in response between a control and the drug being tested is significant. Standard compounds are phenylbutazone at 33 mg./kg. and acetylsalicylic acid at mg./kg., both with oral administration.

The polyarylimidazoles and the pharmaceutically acceptable salts thereof, which are useful anti-inflammatory agents, may be administered either as individual therapeutic agents or as mixtures of therapeutic agents. They may be administered alone, but are generally administered with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice. For example, they may be administered orally in the form of tablets or capsules containing such excipients as starch, milk, sugar or certain types of clay, etc. They may be administered orally in the form of elixirs or oral suspensions with the active ingredients combined with emulsifying and/or suspending agents. They may be injected parenterally, and for this use they, or appropriate derivatives, may be prepared in the form of sterile aqueous solutions. Such aqueous solutions should be suitably bufi'ered, if necessary, and should contain other solutes such as saline or glucose to render them isotonic.

Although the use of the present invention is directed toward the treatment of mammals in general, the preferred subject is humans. In determining an efiicacious dose for human therapy, results of animal testing are frequently extrapolated and a correlation is assumed between animal test behavior and proposed human dosage. When a commercially employed standard is available, the dose level of the clinical candidate in humans is frequently determined by comparison of its performance with the standard in an animal test. For example, phenylbutazone is employed as a standard anti-inflammatory agent and is administered to humans at the rate of 100 to 400 mg. daily. It is assumed, then, that if compounds of the present invention have activity comparable to phenylbutazone in the test assay, that similar doses will provide comparable responses in humans.

Obviously, the physician will ultimately determine the dosage which will be most suitable for a particular individual, and it will vary with the age, weight and response of the particular patient as well as with the nature and extent of the symptoms and the pharmacodynamic characteristics of the particular agent to be administered. Generally, small doses will be administered initially, with a gradual increase in the dosage until the optimum level is determined. It will often be found that when the composition is administered orally, larger quantities of the active ingredient will be required to produce the same level as produced by a small quantity administered parenterally.

Having full regard for the foregoing factors it is considered that an efiective daily dosage of the compounds of the present invention in humans of approximately 10- 500 mg. per day, with a preferred range of about 10 to 200 mg. per day in single or divided doses, or at about 0.1 to 3.0 mg./kg. of body weight will effectively alleviate inflammation in human subjects prone to said disorder. These values are illustrative, and there may, of course, be individual cases where higher or lower dose ranges are merited.

The following examples are provided solely for the purpose of illustration and are not to be construed as limitations of this invention, many variations of which are possible without departing from the spirit or scope thereof.

EXAMPLE I 2-trifluoromethyl-4,5-bis (p-methoxyphenyl) imidazole To 500 ml. of glacial acetic acid containing 20 g. (0.07 mole) of 4,4'-dimethoxybenzil and 40 g. of ammonium acetate, and heated to 100 C., is added dropwise over a 50 minute period 11 g. (0.07 mole) of trifluoroacetaldehyde ethyl-hemiacetal. The resulting reaction mixture is heated to reflux for 2 hours, followed by the addition of Starting with the appropriate diaryldiketone and trifluoroacetaldehyde ethyl hemiacetal, and repeating the procedure of Example I, the following Z-trifluoromethyl imidazoles are prepared:

Employing the procedure of Example I, and starting with the requisite reagents, the following imidazoles are 40 prepared:

2-isobutyl-4,S-diphenylimidazole A yellow suspension of 4.2 g. (0.02 mole) of benzil, 2.0 g. (0.023 mole) of iso-valeraldehyde and 12 g. (0.156 mole) of ammonium acetate in 75 ml. of acetic acid is heated to reflux for 2 hours. An additional 20% of isovaleraldehyde is added and heating continued for an additional 3.5 hours. The reaction mixture is diluted with 400 ml. of water and the clear solution neutralized with ammonium hydroxide. The oil which precipitates is separated from the aqueous layer and dried in vacuo followed by recrystallization from benzene, 0.5 g., M.P. 211- 214 C.

Analysis.Calcd. for C H N (percent): C, 82.5; H, 7.3; N, 10.1. Found (percent): C, 81.9; H, 7.1; N, 9.9.

EXAMPLE VIII Starting with the requisite reagents, and following the procedure of Example VII the following 2-alkyl-4,5-diarylimidazoles are synthesized:

2,4-diphenyl-S-methylimidazole EXAMPLE X Following the procedure of Example IX, and employing the appropriate starting diketone and aldehyde, the following analogs are prepared:

2,4-diphenyl-S-trifluoromethylimidazole To a solution of 1.0 g. (4.5 mmoles) of 1-phenyl-3,3,3- trifluoro-1,2-propanedione in 25 ml. of dry glacial acetic acid under nitrogen is added 2.0 g. of ammonium acetate followed by 573 mg. (5.4 mmoles) of benzaldehyde in ml. of glacial acetic acid. The reaction mixture is heated to reflux for 5.5 hours, cooled to room temperature and added to 400 ml. of ice and water. The pH is adjusted to 7 with ammonium hydroxide solution and the resulting precipitate filtered, washed with water and dried, 858 mg., M.P. ZZZ-224 C. Recrystallization from isopropanel-water provides the purified product, M.P. 234- 234.5 C.

Analysis.-Calcd. for C H F N (percent): C, 66.7; H, 3.9; N, 9.7. Found (percent): C, 66.5; H, 4.0; N, 9.5. Similarly are prepared:

2-(p-methoxy)-4-phenyl-S-trifluoromethylimidazole,

M.P. 253-255 C.;

Z-(p-bromophenyl)-4-phenyl-5-trifluoromethylimidazole,

2-(3-pyridy1)-4-phcnyl-S-trifluoromethylimidazole, M.P.

2- (p-chlorophenyl)-4-phenyl-5-trifluoromethylimidazole,

M.P. 232-245" C. and

2-(p-methylthiophenyl)-4-phenyl-5-trifiuoromethylimidazole, M.P. 222-235 C.

EXAMPLE XII Starting with an appropriately substituted l-aryl-3,3,3- trifluOro-LZ-propanedione and the requisite aldehyde, and employing the experimental conditions of Example XI, the following 2,4 diaryl-S-trifluoromethylimidazoles are prepared:

14 EXAMPLE xur 1-methy1-2-trifluoromethyl-4,S-bis (p-methoxyphenyl) imidazole To a suspension of mg. (2.9 mmoles) of 50% sodium hydride in 5 ml. of dimethylformamide is added 1 g. (2.9 mmoles) of 2-trifluoromethyl-4,5-bis(p-methoxypheny1)imidazole in 20 ml. of the same solvent. After 2 hours of stirring at room temperature the suspension of sodium salt is treated with 410 mg. (2.9 mmoles) of methyl iodide in 10 ml. of dimethylformamide and the reaction mixture heated on a steam bath for 2 hours. The resulting yellow solution is poured into water and the resulting precipitate filtered, dried and recrystallized from hexane, 673 mg., M.P. 127-1295 C.

Analysis.Calcd. for C H F O N (percent): C, 63.0; H, 4.7; N, 7.7. Found (percent): C, 63.2; H, 4.8; N, 7.8.

In a similar manner, employing the appropriate alkylor alkenyl halide the following congeners are prepared:

CHaO 0 CH:

M.P., C,

119 dec,

EXAMPLE XIV Starting with the requisite 2-trifluoro-4,5-diarylimidazole and alkylor alkenyl halide, and repeating the experimental conditions of Example XIII, the following analogs are synthesized:

A tablet base is prepared by blending the following ingredients in the proportion by weight indicated:

The ground dry mixture is placed in vials and sterilized with ethylene oxide after which the vials are sterilely stoppered. For intravenous administration, suflicient water is added to the materials in the vials to form a solution Sucrose, U.S.P. 80.3 Tapioca starch 132 containing mg. of active ingredient per milliliter of in- Magnesium stearate 6.5 lectable sohmon' EXAMPLE XX Into this tablet base there IS blended sufiicient 2-trifluoromethyl-4,5-bis(p-methoxyphenyl)imidazole hydro- Suspension chloride to provide tablets containing 20, 100 and 250 A suspension of 2-trifluoromethyl-4,5-bis(p-tolyl)imidmg. of active ingredient per tablet. The compositions are azole is prepared with the following composition: each compressed into tablets, each weighing 360 mg., by Effective ingredient g 25 0o convntlonal means 70% aqueous sorbitol g 741.29 EXAMPLE XVIII Glyceririe, U.S.P. g 185.35 Capsules} Gum acacia (10% solution) ml 100-00 Polyvinylpyrrolidone g 0.50

A blend is prepared containing the following ingredients:

Distilled water, sufficient to make 1 liter.

To this suspension, various sweeteners and flavorants i i carbonate are added to improve the palatability of the suspension. Dlcalcnim phqsghate The suspension contains approximately 25 mg. of efiec- Magnesium tnsilicate, U.S.P. 5.2 five a em er milliliter Lactose, U.S.P. 5.2 g p Potato starch V 5.2 EXAMPLE XXI Magnesium stearate A 0.8

Magnesium stearate B 0.35 Send dispersion per capsule.

EXAMPLE XIX Injectable preparation One thousand grams of 2-trifiuoromethyl-4,5-bis(p- A solid dispersion containing 20% g trifiuoromethyl- 4,5-bis(p-methoxyphenyl)imidazole and polyethylene glycol 6000 (PEG 6000) is prepared by adding in small portions and with constant stirring g. of the imidazole to 500 g. of PEG 6000 heated to 70 C. When all the compound is added, the melt is flash cooled by cooling in an ice bath and the solidified product reduced to a fine powder and passed through a 100 mesh sieve. The material not passing through is recycled through the melting process.

19 EXAMPLE XXH Each of the following polyarylimidazoles were tested carrageenin rat foot edema test, and were found to have for antiinflammatory activity using the aforedescribed the indicated activity at the specified dose:

TABLE'Co1rtinued Activity Percent Dose, Ar A! R1 R1 inhibition mgJkg.

4-CHaS CuHa 4-CHaO CtHA H 4-CHaS CoH4 26 33 -CHaSCoHa 4-BrCtH4 H 4-CHaSCoHt 9 33 4-CHaSCuH4 H; H 4-CHaSCeH4 42 33 4-CHaSCaH4 4-CHSSC6HI H 4-CHaSCeH4 19 33 4-C2H50 05H CuHs H 4-C2H5O CuH4 36 33 4-FCOH4 d-BrCeHa H 00H; 57 'i-F 00H: 4-CH3O OflHl H 4-FC H 20 33 4-FCuH4 B-pyridyl H 4-FC0H4 13 33 4-CH3C6HI CuHs H 4-CHaCeH4 40 33 0H5 4-CH O 05H H F: 33 CeHs 4-C1C6Hl H CF: 43 33 4-CHsCeH4 4-B1CuH4 H 4-CHaCoH4 40 33 4-n-C4Ho0 CeH. -BrCdih H 4-I1-C4H O 00H 13 33 2-furyl CgHs H 2-furyl 6 33 24ml 4-CH1O CeHl H z-flllyl 6 33 CtHr C H CuHs 16 33 Phenylbutamne b5 33 N z.-. [q -OF3 Indicates an increase in edema.

EXAMPLE XXIII 4 phenyl-2,5-trifluoromethylimidazole To 1.0 g. (4.5 m. moles) of 1-phenyl-3,3,3-trizfluoro- 1,2-propanedione in 25 ml. of dry glacial acetic acid is added 2.0 g. ammonium acetate followed by the dropwise addition of 778 mg. (5.4 m. moles) of trifluoroacetaldehyde ethyl hemiacetal in 10 ml. of the same solvent. The reaction mixture is heated to reflux for 1.5 hours and an additional 778 mg. of the hemiacetal added and refluxing continued for 2 hours. The clear solution is poured into 200 ml. of Water, the pH adjusted to 7.0 with ammonium hydroxide and extracted with 2x200 ml. of ethyl acetate. The organic layer is separated, dried over sodium sulfate and concentrated under reduced pressure to dryness. The residue is triturated with hexane and the resulting solids filtered, 598 mg, M.P. 158-164 C.

Analysis.Calcd. for C H F N (percent): C, 47.2; H, 2.2; N, 10.0. Found (percent) C, 47.5; H, 2.5; N, 99.

EXAMPLE XXIV Starting with an appropriate substituted 1-aryl-3,3,3-trifluoro-l,2-propanedione and trifiuoroacetaldehyde ethyl hemiacetal, and following the procedure of Example XXIII, the following 2,S-trifiuoromethylimidazoles are prepared:

Ar 0 Fa I NH Ar Ar 4-FC6H4 3412115005114 1-01001; 2-fury l 4-CHaO C0 4 4-CHsSCeHt 2-BrCaH4 EXAMPLE XXV 2,3-bis (p-methoxyphenyl) -l,4-diazaspiro[4,5] deca-1,3-diene filtrate concentrated to an oil which is crystallized from isopropanol-water, 1.6 g., M.P. 85-88 C.

Analysis.-Calcd. for C H N O (percent) C, 75.9; H,.6.9; N, 8.1. Found (percent): C, 75.6; H, 7.1; N, 8.0.

In a similar manner the following compounds are prepared:

N X Ra R4 Ar Ar R; R4 M.P., C.

CH; CH: 76-79 2) s- 103-106 4-CH3OC5H4 4-CH3OC5H4 CH3 CH3 88-91 EXAMPLE XXVI Starting with the appropriate benzil and ketone, and repeating the procedure of Example XXV, the following analogs are synthesized:

Ar Ar l N In vivo activity on acute experimental synovitis in dogs Dog Number 1 2 3 4 5 Control Knee Pressure 1 22 26 22 23 32 Test Knee Pressure 1 3 11 5 2 1 Pressure is reported in mm. Hg.

Decrease in the joint pressure due to a reduction of infiammation is taken as an indication of activity.

EXAMPLE XXVIII In vitro inhibition of platelet aggregation The ability of the compounds of the present invention to inhibit platelet aggregation in vitro is measured according to the method of Born et al., J. Physiol., 168, 178 (1963) and modified by Constantine, Nature, 205, 1075 (1965) and comprises the following procedure:

Anesthetized male rabbits are bled from a carotid artery into plastic centrifuge tubes containing 0.1 volume 3% sodium citrate. Platelet-rich plasma is separated by centrifugation at 100 G for minutes at C. Plasma from 3 animals is pooled; 5 ml. samples are placed into clear plas-. tic cuvettes and stirred at 1000 r.p.m., followed by the addition of compounds of the present invention at levels of 6 l0 10- and 10 moles/liter. After 10 minutes of incubation with the platelet-rich plasma at room temperature, collagen, a protein known to cause platelet aggregation, is added (0.27 ml. collagen/4 mi. plasma) and changes in the optical density are followed with a Spectronic 20 colorimeter attached to a Houston Instrument TY Recorder. Platelet aggregation is indicated by a decrease in optical density. The relative potency of compounds are thus rated on their ability to inhibit (percent) collagen induced platelet aggregation.

When 2 trifluoromethyl 4,5-bis (p methoxyphenyl) imidazole is tested according to the above procedure the following results are obtained for rabbit, dog and human plasma:

EXAMPLE XXIX In vivo inhibition of platelet aggregation The capacity of the compounds of the present invention to inhibit platelet aggregation in a modified in vivo test reported by Constantine, Nature, 214, 1084 (1967) and is measured by the following procedure:

Unanesthetized fasted adult mongrel dogs of either sex are dosed orally (P.O.) at mg./kg. with a solid dispersion of 2-trifiuoromethyl 4,5 bis(p methoxyphenyl) imidazole in polyethylene glycol. Blood samples are taken at hourly intervals and placed in plastic centrifuge tubes containing 0.1 volume 3% sodium citrate. Platelet-rich plasma is separated by centrifugation at 100 G for 10 minutes at 80 C. and treated with a collagen suspension in saline. Changes in optical density are then followed with a Spectronic 20 colorimeter attached to a Houston Instrument TY Recorder. Platelet aggregation is indicated by a decrease in optical density, and the inhibition of collagen induced aggregation is reported a positive or negative. Measurements are carried out on the hourly samples, allowing for the determination of a duration of the initial effect.

24 Dog No.2 Response (duration) 1' Positive (30 min-48 hrs.) 2 Positive (2 hrs.72 hrs.)

PREPARATION A DIARYLDIKETONES The following diaryl-a-diketones, not previously reported in the chemical literature, are synthesized via a selenium dioxide oxidation of the corresponding monoketone, essentially the method taught by Hatt et al., J. Chem. Soc., 93 (1936), wherein desoxybenzoin is oxidized to benzil:

ALKYLARYLDIKETONES (a) 1 phenyl 3,3,3-trifiuoro-1,2-propanedione monohydrate.-Trifiuoromethyl benzyl ketone (13.7 g., 0.072 mole), prepared according to the method of Nes et al., J. Am. Chem. Soc., 72, 5409 (1950), is added to a suspension of 8.8 g. (0.079 mole) of selenium dioxide in 300 ml. of glacial acetic acid and the reaction mixture heated to C. for 3 hours. The mixture is then cooled, the selenium filtered and the filtrate poured into 1500 ml. of water. The hazy solution is extracted with ether and the ether extracts washed free of acetic acid by repeated washings with 10% aqueous sodium bicarbonate. The extracts are dried over calcium sulfate, concentrated to a semi-solid and the residue recrystallized from petroleum ether, 4.1 g., M.P. 83-85 C. Additional amounts of the product are obtainable by concentration of the recrystallization mother liquors.

Analysis.--Calcd. for C H F O (percent): C, 49.2; H, 32. Found (percent): C, 48.6; H, 3.2.

Following the procedure of Nes et al., and the oxidation described above, the following alkylaryldiketones, not previously reported in the literature, are synthesized:

25 PREPARATION C Aryl-arylmethyl ketones 2. The method of claim 1, Formula I, wherein Ar and Ar are each substitued phenyl and R is hydrogen.

3. The method of claim 1, Formula I, wherein Ar is phenyl, Ar is substituted phenyl and R is hydrogen.

4. The method of claim 1, Formula I, wherein Ar and Ar are each substituted phenyl and R is methyl.

5. The method of claim 1, Formula I, wherein Ar and Ar are each phenyl and R is hydrogen.

6. The method of claim 2, wherein R is trifiuoromethyl and Ar and Ar are each p-methoxyphenyl.

7. The method of claim 2 wherein R is trifiuoromethyl and Ar and Ar are each p-methylthiophenyl.

8. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar are each o-methoxyphenyl.

9. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar are each m-methoxyphenyl.

Ar Ar Ar R; Ar R,

N N-Ri N N-R and R1N N Y Ar Ar (II) (III) and the pharmaceutically acceptable acid addition salt thereof,

wherein:

Ar and Ar are each selected from the group consisting of furyl, thienyl, pyridyl, phenyl and substituted phenyl wherein said substituents are selected from the group consisting of fluorine, chlorine, bromine, alkyl, alkoxy and alkylthio each containing from 1 to 4 carbon atoms and 3,4-dimethoxy;

R is selected from the group consisting of hydrogen, alkyl containing from 1 to 4 carbon atoms and alkenyl containing from 3 to 4 carbon atoms; and

R is selected from the group consisting of trifluoromethyl, alkyl containing from 1 to 4 carbon atoms, furyl, thienyl, pyridyl, phenyl and substituted phenyl wherein said substituents are selected from the group consisting of fluorine, chlorine, bromine, trifluoromethyl, alkyl, alkoxy and alkylthio each containing from 1 to 4 carbon atoms, 3,4-dimethoxy and 2,4-dichloro.

10. The method of claim 2 wherein R is tribuoromethyl and Ar and Ar are each p-fluorophenyl.

11. The method of claim 2 wherein R is trifiuoromethyl and Ar and Ar are each p-n-butoxyphenyl.

.12. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar' are each 3,4-dimethoxyphenyl.

13. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar are each p-ethoxyphenyl.

14. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar are each p-bromophenyl.

15. The method of claim 2 wherein R is trifluoromethyl and Ar and Ar are each p-tolyl.

16. The method of claim 2 wherein R is phenyl and Ar and Ar are each p-methoxyphenyl.

17. The method of claim 2 wherein R is isobutyl and Ar and A1" are each p-methoxyphenyl.

18. The method of claim 3 wherein R is trifiuoromethyl and Ar is p-bromophenyl.

19. The method of claim 3 wherein R is trifluoromethyl and Ar is p-methoxyphenyl.

20. The method of claim 4 wherein R is trifluoromethyl and Ar and AI are each p-rnethoxyphenyl.

21. The method of claim 5 wherein R is p-bromophenyl.

References Cited Biltz, Chem. Abst., vol. 1, pp. 2605-6 (1907).

Carrara et al., Chem. Abst., vol. 40, col. 7241 (1946). Raasch, Chem. Abst., v01. 57, col. 4520-1 (1962). Yak, J. Med. Pharm. Chem, vol. 1, pp. 121-33 (1959).

STANLEY J. FRIEDMAN, Primary Examiner F. E. WADDELL, Assistant Examiner US. Cl. X.R. 424-263 

